Bonding apparatus

ABSTRACT

With an assumption that the three data of the position (X&lt;SUB&gt;1&lt;/SUB&gt;, Y&lt;SUB&gt;1&lt;/SUB&gt;) of the first positioning pattern 202 and position (X&lt;SUB&gt;2&lt;/SUB&gt;, Y&lt;SUB&gt;2&lt;/SUB&gt;) of the second positioning pattern 212 of the reference chip 200, and the position (X&lt;SUB&gt;3&lt;/SUB&gt;, Y&lt;SUB&gt;3&lt;/SUB&gt;) of the first positioning pattern 232 of the bonding object chip 230, as well as the length L of a line segment connecting (X&lt;SUB&gt;1&lt;/SUB&gt;, Y&lt;SUB&gt;1&lt;/SUB&gt;) and (X&lt;SUB&gt;2&lt;/SUB&gt;, Y&lt;SUB&gt;2&lt;/SUB&gt;), and the angle theta&lt;SUB&gt;2 &lt;/SUB&gt;of this line segment with respect to the X axis, are known, the coordinates (X&lt;SUB&gt;4&lt;/SUB&gt;, Y&lt;SUB&gt;4&lt;/SUB&gt;) of the center position of the imaging range 250 that is to be imaged next is determined by detecting the inclination-angle Deltatheta of the first positioning pattern 232 of the bonding object chip 230. Furthermore, the imaging range can be narrowed and the second positioning pattern 252 can be captured by increasing the precision of Deltatheta.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to bonding and more particularly to abonding method, bonding apparatus and bonding program in which thepositions of a plurality of positioning patterns disposed on a chip thatis the object of bonding are respectively detected, the positions ofbonding pads that are in a specified positional-relationship with theplurality of positioning patterns are calculated, and bonding isperformed in the calculated bonding positions. 2. Description of theRelated Art

In wire bonding between a plurality of bonding pads disposed on a chipand a plurality of bonding leads disposed on a circuit board, etc., onwhich the chip is mounted, the bonding of wires is accomplished bymoving a bonding tool to the positions of the respective bonding padsand the positions of the respective bonding leads. As chips have becomesmaller and more highly integrated, the dimensions of bonding pads havebecome smaller and the spacing of such bonding pads has become narrower;accordingly, the accurate specification of the positions of therespective bonding pads has become necessary. Accordingly, positiondetection of bonding pads and the positioning patterns used in bondingis practiced.

However, when chips are disposed so that these chips are shifted in thedirection of rotation, an inclination is generated in the positioningpatterns, etc., so that accurate position detection cannot beaccomplished, and wire bonding cannot be performed correctly. JapanesePatent Application Laid-Open (Kokai) No. S63-56764 discloses a method inwhich pattern matching between a reference-image prepared beforehand andthe object-image is performed by successively rotating thereference-image from 0 to 360° for each pattern matching in cases wherethere is rotation, repeating pattern matching for each angle, andjudging the locations and angles that show the best match as a result.

Furthermore, in the method of Japanese Patent No. 2864735, squareregions that are to be compared are extracted from object-image signalsobtained by imaging, the image signals contained in the extracted squareregions are converted into image signals with polar coordinates by wayof using the corners of the square regions as the origin,radial-direction patterns for respective specified angles andradial-direction patterns in the reference angles of reference-imagesprepared beforehand and subjected to a polar coordinate conversion aresuccessively compared, and the comparative angle of the object-image iscalculated.

Furthermore, in Japanese Patent Application Laid-Open (Kokai) No.2002-208010, an approach using a rotation-resistant reference point isdisclosed as a means for performing high-precision position detectionwithout performing pattern matching in the rotational direction (whichtends to involve an increase in the quantity of calculations) even incases where the object of comparison is disposed in an attitude thatincludes positional deviation in the rotational direction. Here,according to Japanese Patent Application Laid-Open (Kokai) No.2002-208010, the term “rotation-resistant reference point” refers to apoint which is such that the error in the position of the object ofcomparison that is detected in pattern matching of the reference-imageand an image of the object of comparison that is obtained by imaging theobject of comparison disposed in an attitude that includes positionaldeviation in the direction of rotation shows a minimum value.

Furthermore, in Japanese Patent Application Laid-Open (Kokai) No.2002-208010, it is indicated that normalized correlation calculationscan be used as one method of pattern matching. Moreover, the followingembodiment is indicated as a method for calculating therotation-resistant reference point.

In the first embodiment, the rotation-resistant reference point iscalculated as follows. Specifically, with one corner of thereference-image taken as the center, a rotated image that is rotated +Q°is produced, and the coordinates (X₁, Y₁) of the point showing the bestmatch as a result of pattern matching between this rotated image and thereference-image are determined. Similarly, a rotated image that isrotated −Q° is produced, and the coordinates (X₂, Y₂) of the pointshowing the best match as a result of pattern matching between thisrotated image and the reference-image are determined. The coordinates(AX1, AY1) of the rotation-resistant reference point are expressed bythe following Equations (1) through (4) using the coordinates (X₁, Y₁),(X₂, Y₂) of these two points, the angle Q° and the coordinates (XC1,YC1) of the corner point taken as the center of rotation.AX1=XC1+r·cos α  (1)AY1=YC1+r·sin α  (2)Here, α=tan⁻¹{(X ₂ −X ₁)/(Y ₁ −Y ₂)}  (3)r=√{(X ₂ −X ₁)²+(Y ₁ −Y ₂)/²}/2sin Q  (4)

The rotation-resistant reference point determined by this method is thecenter of the object in cases where the pattern used is the shape of theobject. For example, in the case of a circle, the center point of thecircle is the rotation-resistant reference point, and in the case of asquare, the center point of the square is the rotation-resistantreference point.

The second embodiment is a simpler method for calculating therotation-resistant reference point. Specifically, a plurality ofrotational center points are set within the reference-image. Then, thereference-image is rotated +Q° about each rotational center point. Theamounts of matching between the respective rotated images thus obtainedand the reference-image are respectively calculated. Then, a rotationalcenter point with a relatively large amount of matching (among theplurality of rotational center points) is taken as therotation-resistant reference point. In this case, a rotational centerpoint that is set in the vicinity of the center of the pattern used istaken as the rotation-resistant reference point.

It is indicated that the coordinates of points used in bonding can bedetermined with high precision, without any need to perform patternmatching in the rotational direction, by thus calculating thecoordinates of the rotation-resistant reference point, and taking thispoint as a bonding alignment point, i.e., a bonding positioning point.

In regard to position detection of positioning patterns, etc., newtechniques have been developed as shown below as a demand for increasedwire bonding speed has appeared; along with these new techniques, newproblems have arisen.

For example, as the scale of LSI has increased, the number of boningpads has increased, and detection of the individual positions of all ofthese pads takes time. Accordingly, a method is practiced in which onlythe positions of positioning patterns, at least two of which are spacedas widely as possible on the surface of the chip, are detected, thepositions of the other bonding pads are obtained by calculation basedupon these positions, and the calculated positions are taken as thebonding target positions.

Furthermore, in cases where wire bonding is performed for numerous typesof chips, the storage in memory and read-out of the disposition ofpositioning patterns and bonding pads on the chip according to the typeinvolved is also bothersome. Accordingly, a method in which a referencechip that acts as a reference for the type of chip involved is preparedwhen there is a change in the chip type, the disposition relationship ofthe positioning patterns and bonding pads is stored in memory astraining for this reference chip, next, positioning patterns are imagedfor the chip that is the object of bonding as the running state, andposition detection is accomplished by pattern matching with the acquiredimage of the reference chip, is also practiced.

If an even greater increase in speed is required, a considerableprocessing time is required for the pattern recognition of a pluralityof positioning patterns in the same visual field; accordingly, a methodis performed in which only the areas in the vicinity of the respectivepositioning patterns are imaged, and positional detection isaccomplished by performing pattern matching based upon these images.

Thus, as the speed progressively increases, the question of how todiscriminate a plurality of positioning patterns and detect thepositions of these patterns in a short time becomes an importantperformance factor in wire bonding apparatuses.

In this case, it has been demonstrated that if there is a deviation ofthe chip in the rotational direction, i.e., an inclination, this hindersan increase in the speed of position detection. The conditions of thisproblem will be described with reference to FIGS. 1 and 2, which showthe relationship between the reference chip and the acquired image ofthe bonding chip. FIG. 1 shows a case in which the bonding object chip230 is not inclined with respect to the reference chip 200, and FIG. 2shows a case in which the bonding object chip 230 is inclined withrespect to the reference chip 200. In FIGS. 1 and 2, the positioningpatterns 202, 212, 232 and 252 are disposed on the upper left cornersand lower right corners of the chips 200 and 230.

The training in regard to the reference chip 200 may be described asfollows. A first reference-image 204 that includes the first positioningpattern 202 disposed on the upper left corner is acquired, and a secondreference-image 214 that includes the second positioning pattern 212disposed on the lower right corner is similarly acquired. Theseimaging-positions are detected by the wire bonding apparatus, and arerespectively stored in memory as the center position 206 of the firstreference-image and the center position 216 of the secondreference-image. These center positions are treated as the position ofthe first positioning pattern 202 and the position of the secondpositioning pattern 212, and the respective positions of numerousbonding pads (not shown in the drawings) are calculated based upon thesepositions.

When training is completed, detection of the positioning patterns on thebonding object chip 230 is performed as a running step. First, thebonding object chip 230 is imaged in the position where the firstpositioning pattern 202 of the reference chip 200 was imaged. As shownin FIG. 1, a portion of the bonding object chip 230 is observed in thisimaging range 220. Because of requirements for an increased opticalmagnification in order to ensure precision and the above-describedincrease in speed, this imaging range 220 is limited to a narrow range,so that the second positioning pattern 252 of the bonding object chip230 is not observed. The position of the first positioning pattern 232of the imaged bonding object chip 230 is shifted with respect to theposition 206 of the first positioning pattern 202 of the reference chip200. The position of the first positioning pattern 232 of the bondingobject chip 230 can be determined by pattern matching, by moving thefirst reference-image 204 in parallel from the position 206, and usingthe moved position 236 of the first reference-image where this firstpositioning pattern 202 and the first positioning pattern 232 of thebonding object chip 230 show the greatest amount of overlapping.

Next, the camera must be moved in order to image the second positioningpattern of the bonding object chip 230. Besides the information that wasacquired in training, i.e., the position 206 of the first positioningpattern 202 and position 216 of the second positioning pattern 212 ofthe reference chip 200, and the positions of the respective bonding padscalculated based upon these positions, the information that is obtainedin this case is only the position 236 of the first positioning patternof the bonding object chip 230. Accordingly, as shown in FIG. 1, withthe point 236, point 206 and point 216 taken as three of the four pointsthat form a parallelogram, the remaining one point 246 is calculated.This is viewed as the position of the second positioning pattern of thebonding object chip 230, and the center of the imaging range 240 of thecamera is moved to this position.

In the case of FIG. 1, since the bonding object chip 230 is notinclined, the movement of the above-described camera involves noproblem; the camera movement is performed at a high speed, and imagingof the second positioning pattern of the bonding object chip 230 isperformed. If the bonding object chip 230 is inclined as shown in FIG.2, then the position 256 of the actual second positioning pattern 252may be located outside of the imaging range 240 of the moved camera.Especially in cases where an attempt is made to increase the speed bynarrowing the imaging range, there is a possibility of an increasednumber of instances in which the second positioning pattern 252 that isto be imaged cannot be captured within the imaging range of the movedcamera because of the effects of this inclination. If the secondpositioning pattern 252 is not captured within the imaging range 240,for example, the operator must perform a search while viewing the visualfield of the camera after the apparatus is stopped by a recognitionerror, and must determine a position that allows the second positioningpattern to be captured. Accordingly, the processing time is greatlyincreased. If the imaging range is therefore made wider, the processingtime required for pattern matching, etc., is increased. Furthermore, inorder to broaden the imaging range, it is necessary to reduce theoptical magnification, so that the problem of a drop in precisionaccompanying this reduction of the optical magnification also arises.Furthermore, in cases where a pattern resembling the reference patternis present within a second visual field, there may be cases in whicherroneous detection resulting from pattern matching with this similarpattern occurs. Accordingly, the following problem arises: namely, as aresult of this erroneous detection, bonding cannot be performed in thedesired pad positions on the chip, so that a defective product ismanufactured.

Thus, in cases where there is a deviation of the chip in the directionof rotation, i.e., an inclination, this hinders the increase in thespeed of movement to the imaging-position of the next positioningpattern, so that the productivity of the wire bonding apparatus cannotbe improved. On the other hand, in the conventional techniques describedin the above-described Japanese Patent Application Laid-Open (Kokai) No.S63-56764, Japanese Patent No. 2864735, and Japanese Patent ApplicationLaid-Open (Kokai) No. 2002-208010, inclination-angle detection andposition detection are performed with the acquired image as an object.Accordingly, there is no description of the capturing of the positioningpattern in the next imaging-position in any of these techniques.

Furthermore, in Japanese Patent Application Laid-Open (Kokai) No.S63-56764 and Japanese Patent No. 2864735, a detection of theinclination-angle is described; however, there is no description of therelationship between this inclination-angle and the capturing of thepositioning pattern in the next imaging-position. In the method in whichangle detection is performed using a polar coordinate conversion inJapanese Patent No. 2864735, the precision of inclination-angledetection is greatly influenced by the manner in which the origin isset. For example, in cases where the positioning patterns are circular,polar coordinate development can be performed with good reproducibilityif the center of each circle is taken as the origin for polar coordinatedevelopment. However, there is no angular dependence of the developmentpattern, so that angle detection is in fact impossible. In cases wherethe positioning patterns have an asymmetrical shape, the conditions ofthe development pattern differ according to the location of the originof polar coordinate development; as result, the precision of angledetection is affected. Japanese Patent No. 2864735 discloses a method inwhich respective polar coordinate conversions are performed for the fourcorners of square regions, and the inclination-angle is determined basedupon these conversions. In this case, however, the processing time islong.

Furthermore, in the method of Japanese Patent Application Laid-Open(Kokai) No. 2002-208010, a rotation-resistant reference point iscalculated, and this point is used as a bonding positioning point, makesit possible to determine the positions with a high degree of precision.However, the inclination-angles of the positioning patterns cannot bedetermined.

Thus, in the prior art, in cases where the positioning patterns have aninclination-angle, problems remain in terms of how to move quickly tothe next imaging-position.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to solve such problemsencountered in the prior art, and to provide a bonding method, bondingapparatus and bonding program that make it possible to move to the nextimaging-position at a higher speed even in cases where the positioningpatterns have an inclination-angle.

The present invention is based on the results of an investigation of thequestion of where to locate the origin so as to improve the precision inthe detection of the inclination-angle by way of using a polarcoordinate conversion, focusing on the fact that a means for clarifyingthe relationship between the inclination-angle of one positioningpattern and the imaging-position of the next positioning pattern havebeen devised, and on the fact that the positioning processing time canbe shortened as the precision of this inclination-angle is improved.First, the means for clarifying the relationship between theinclination-angle and the next imaging-position will be described; then,the principle involved in the improvement of the precision of theinclination-angle will be described.

The above object is accomplished by unique steps of the presentinvention for a bonding method that detects each one of positions of aplurality of positioning patterns disposed on a chip that is the objectof bonding, calculates positions of bonding pads that are in a specifiedpositional-relationship with the plurality of positioning patterns, andperforms bonding in calculated positions of the bonding pads; and in thepresent invention, the bonding method includes:

-   -   a first reference-image acquisition step that makes an image of        a first positioning pattern among the plurality of positioning        patterns for a reference chip which is used as a reference for        the detection of the positions of the positioning patterns, thus        acquiring an image thus obtained as a first reference-image;    -   a first object-image acquisition step that makes an image of the        first positioning pattern for a chip that is the object of        bonding, thus acquiring an image thus as a first object-image;    -   a first positional-relationship calculation step that moves the        first positioning pattern of the first reference-image and the        first positioning pattern of the first object-image in relative        terms so as to superimpose both of said images, so that a first        positional-relationship which is the relative        positional-relationship between the first positioning pattern of        the reference chip and the fist positioning pattern of the        bonding object chip from the amount of said movement is        calculated;    -   an inclination-angle calculation step that calculates an        inclination-angle of the first positioning pattern of the        bonding object chip with respect to the first positioning        pattern in the reference chip;    -   a second reference-image acquisition step that makes an image of        a second positioning pattern which is in a specified        positional-relationship with the first positioning pattern for        the reference chip, thus acquiring an image thus obtained as a        second reference-image;    -   an imaging-position calculation step that calculates a second        positioning pattern imaging-position in which the second        positioning pattern is imaged for the chip that is the object of        bonding, wherein said second positioning pattern        imaging-position is calculated based upon the first        positional-relationship, the inclination-angle, a specified        inter-pattern positional-relationship and the imaging-position        in the first object-image acquisition step;    -   a second object-image acquisition step that makes an image of        the second positioning pattern for the bonding object chip in        the calculated second positioning pattern imaging-position, thus        acquiring the image thus obtained as a second object-image; and    -   a second positional-relationship calculation step that moves the        second reference-image and the second object-image in relative        terms so as to superimpose the second positioning pattern of the        second reference-image and the second positioning pattern of the        second object-image, so that a second positional-relationship        which is the relative positional-relationship between the second        positioning pattern of the reference chip and the second        positioning pattern of the bonding object chip from the amount        of said movement is calculated; and    -   positions of the bonding pads are calculated based upon the        first positional-relationship and second        positional-relationship, and bonding is performed.

In the above bonding method of the present invention, it is preferablethat

-   -   the inclination-angle calculation step include:        -   a reference conversion origin specifying step that specifies            the conversion origin that is used to subject the first            reference-image to a polar coordinate conversion;        -   a reference-image conversion step that performs a polar            coordinate conversion on the first reference-image by way of            using the specified reference conversion origin, thus            producing a post-conversion reference-image;        -   an object conversion origin specifying step that specifies            the conversion origin that is used to subject the first            object-image to a polar coordinate conversion by a            positional-relationship that is the same as the            positional-relationship between the first positioning            pattern and the reference conversion origin in the first            reference-image, based upon the calculated first            positional-relationship;        -   an object-image conversion step that performs a polar            coordinate conversion on the first object-image by way of            using the specified object conversion origin, thus producing            a post-conversion object-image; and        -   a relative inclination-angle calculation step that moves the            post-conversion object-image and post-conversion            reference-image in relative terms on the angular axis so            that the first positioning pattern that has been subjected            to a polar coordinate development in the post-conversion            object-image and the first positioning pattern that has been            subjected to a polar coordinate development in the            post-conversion reference-image are superimposed, so that            the relative inclination-angle between the positioning            pattern of the reference chip and the positioning pattern of            the bonding object chip is calculated from the angular            amount of said movement; and    -   the reference conversion origin specifying step include:        -   a rotated image acquisition step that acquires a rotated            image produced by rotating the first reference-image through            a specified angle, and        -   a pattern matching step that moves the first reference-image            and the rotated image in relative terms, thus performing            pattern matching so that the positioning pattern of the            first reference-image and the positioning pattern of the            rotated image are superimposed; and    -   a reference conversion origin. which is such that the error in        the relative positional-relationship between the two positioning        patterns detected by pattern matching of an image that is the        object of comparison obtained by imaging-positioning patterns        disposed in an attitude that includes positional deviation in        the direction of rotation, and a first reference-image obtained        by imaging-positioning patterns containing no positional        deviation in the direction of rotation shows a minimal value, is        specified, based upon the results of the pattern matching.

Furthermore, in the above-described bonding method of the presentinvention, it is preferable that:

-   -   the inclination-angle calculation step include:        -   a reference conversion origin specifying step that specifies            the conversion origin that is used to subject the first            reference-image to a polar coordinate conversion;        -   a reference-image conversion step that performs a polar            coordinate conversion on the first reference-image by way of            using the specified reference conversion, thus producing the            post-conversion reference-image;        -   an object conversion origin specifying step that specifies            the conversion origin that is used to subject the first            object-image to a polar coordinate conversion by a            positional-relationship that is the same as the            positional-relationship between the first positioning            pattern and the reference conversion origin in the first            reference-image, based upon the calculated first            positional-relationship;        -   an object-image conversion step that performs a polar            coordinate conversion on the first object-image by way of            using the specified object conversion origin, thus producing            the post-conversion object-image; and        -   a relative inclination-angle calculation step that moves the            post-conversion image and post-conversion reference-image in            relative terms on the angular axis so that the first            positioning pattern that has been subjected to a polar            coordinate development in the post-conversion object-image            and the first positioning pattern that has been subjected to            a polar coordinate development in the post-conversion            reference-image are superimposed, thus calculating the            relative inclination-angle between the positioning pattern            of the reference chip and the positioning pattern of the            bonding object chip from the angular amount of said            movement; and    -   the reference conversion origin specifying step include:        -   a rotational center point setting step that sets a plurality            of rotational center points in arbitrary positions within            the first reference-image,        -   a rotated image acquisition step that acquires rotated            images by rotating the first reference-image through a            specified angle about each of the rotational center points,            and        -   a matching amount calculation step that calculates the            amount of pattern matching which indicates, for each of the            rotated images, the degree of overlapping between the            positioning pattern of the rotated image and the positioning            pattern of the first reference-image; and        -   wherein a rotational center, whose pattern matching amount            is within a specified range from a maximum value thereof, or            a point, which is within a proximate region of said            rotational center, is specified as a reference conversion            origin in which an error in a relative            positional-relationship between both positioning patterns            detected by pattern matching of an image of an object of            comparison, which is obtained by imaging a positioning            pattern disposed in an attitude that includes positional            deviation in the direction of rotation, and a            reference-image, which is obtained by imaging a positioning            pattern containing no positional deviation in the direction            of rotation, shows a minimal value.

In addition, it is preferable that the above-described secondobject-image acquisition step image the second positioning pattern in animaging range that is narrower than the imaging range used in the firstobject-image acquisition step.

The above-described object is also accomplished by a unique structure ofthe present invention for a bonding apparatus that detects each one ofpositions of a plurality of positioning patterns disposed on a chip thatis the object of bonding, calculates positions of bonding pads that arein a specified positional-relationship with the plurality of positioningpatterns, and performs bonding in calculated positions of the bondingpads; and in the present invention, the bonding apparatus includes:

-   -   a first reference-image acquisition means that makes an image of        a first positioning pattern among the plurality of positioning        patterns for a reference chip which is used as a reference for        the detection of the positions of the positioning patterns, thus        acquiring an image thus obtained as a first reference-image;    -   a first object-image acquisition means that makes an image of        the first positioning pattern for a chip that is the object of        bonding, thus acquiring an image thus as a first object-image;    -   a first positional-relationship calculation means that moves the        first positioning pattern of the first reference-image and the        first positioning pattern of the first object-image in relative        terms so as to superimpose both of said images, so that a first        positional-relationship which is the relative        positional-relationship between the first positioning pattern of        the reference chip and the fist positioning pattern of the        bonding object chip from the amount of said movement is        calculated;    -   an inclination-angle calculation means that calculates an        inclination-angle of the first positioning pattern of the        bonding object chip with respect to the first positioning        pattern in the reference chip;    -   a second reference-image acquisition means that makes an image        of a second positioning pattern which is in a specified        positional-relationship with the first positioning pattern for        the reference chip, thus acquiring an image thus obtained as a        second reference-image;    -   an imaging-position calculation means that calculates a second        positioning pattern imaging-position in which the second        positioning pattern is imaged for the chip that is the object of        bonding, wherein said second positioning pattern        imaging-position is calculated based upon the first        positional-relationship, the inclination-angle, a specified        inter-pattern positional-relationship and the imaging-position        in the first object-image acquisition step;    -   a second object-image acquisition means that makes an image of        the second positioning pattern for the bonding object chip in        the calculated second positioning pattern imaging-position, thus        acquiring the image thus obtained as a second object-image; and    -   a second positional-relationship calculation means that moves        the second reference-image and the second object-image in        relative terms so as to superimpose the second positioning        pattern of the second reference-image and the second positioning        pattern of the second object-image, so that a second        positional-relationship which is the relative        positional-relationship between the second positioning pattern        of the reference chip and the second positioning pattern of the        bonding object chip from the amount of said movement is        calculated; and    -   positions of the bonding pads are calculated based upon the        first positional-relationship and second        positional-relationship, and bonding is performed.

In the above structure of the bonding apparatus of the presentinvention, it is preferable that

-   -   the inclination-angle calculation means include:        -   a reference conversion origin specifying means that            specifies the conversion origin that is used to subject the            first reference-image to a polar coordinate conversion;        -   a reference-image conversion means that performs a polar            coordinate conversion on the first reference-image by way of            using the specified reference conversion origin, thus            producing a post-conversion reference-image;        -   an object conversion origin specifying means that specifies            the conversion origin that is used to subject the first            object-image to a polar coordinate conversion by a            positional-relationship that is the same as the            positional-relationship between the first positioning            pattern and the reference conversion origin in the first            reference-image, based upon the calculated first            positional-relationship;        -   an object-image conversion means that performs a polar            coordinate conversion on the first object-image by way of            using the specified object conversion origin, thus producing            a post-conversion object-image; and        -   a relative inclination-angle calculation means that moves            the post-conversion object-image and post-conversion            reference-image in relative terms on the angular axis so            that the first positioning pattern that has been subjected            to a polar coordinate development in the post-conversion            object-image and the first positioning pattern that has been            subjected to a polar coordinate development in the            post-conversion reference-image are superimposed, so that            the relative inclination-angle between the positioning            pattern of the reference chip and the positioning pattern of            the bonding object chip is calculated from the angular            amount of said movement; and    -   the reference conversion origin specifying means include:        -   a rotated image acquisition means that acquires a rotated            image produced by rotating the first reference-image through            a specified angle, and        -   a pattern matching means that moves the first            reference-image and the rotated image in relative terms,            thus performing pattern matching so that the positioning            pattern of the first reference-image and the positioning            pattern of the rotated image are superimposed; and    -   a reference conversion origin, which is such that an error in        the relative positional-relationship between the two positioning        patterns detected by pattern matching of an image that is the        object of comparison obtained by imaging-positioning patterns        disposed in an attitude that includes positional deviation in        the direction of rotation, and a first reference-image obtained        by imaging-positioning patterns containing no positional        deviation in the direction of rotation shows a minimal value, is        specified, based upon the results of the pattern matching

Furthermore, the above-described object is accomplished by uniqueprocesses of the present invention for a bonding program that detectseach one of positions of a plurality of positioning patterns disposed ona chip that is the object of bonding, calculates positions of bondingpads that are in a specified positional-relationship with the pluralityof positioning patterns, and performs bonding in calculated positions ofthe bonding pads; and in the present invention, the bonding programincludes:

-   -   a first reference-image acquisition process that makes an image        of a first positioning pattern among the plurality of        positioning patterns for a reference chip which is used as a        reference for the detection of the positions of the positioning        patterns, thus acquiring an image thus obtained as a first        reference-image;    -   a first object-image acquisition process that makes an image of        the first positioning pattern for a chip that is the object of        bonding, thus acquiring an image thus as a first object-image;    -   a first positional-relationship calculation process that moves        the first positioning pattern of the first reference-image and        the first positioning pattern of the first object-image in        relative terms so as to superimpose both of the images, so that        a first positional-relationship which is the relative        positional-relationship between the first positioning pattern of        the reference chip and the fist positioning pattern of the        bonding object chip from the amount of said movement is        calculated;    -   an inclination-angle calculation process that calculates an        inclination-angle of the first positioning pattern of the        bonding object chip with respect to the first positioning        pattern in the reference chip;    -   a second reference-image acquisition process that makes an image        of a second positioning pattern which is in a specified        positional-relationship with the first positioning pattern for        the reference chip, thus acquiring an image thus obtained as a        second reference-image;    -   an imaging-position calculation process that calculates a second        positioning pattern imaging-position in which the second        positioning pattern is imaged for the chip that is the object of        bonding, wherein said second positioning pattern        imaging-position is calculated based upon the first        positional-relationship, the inclination-angle, a specified        inter-pattern positional-relationship and the imaging-position        in the first object-image acquisition step;    -   a second object-image acquisition process that makes an image of        the second positioning pattern for the bonding object chip in        the calculated second positioning pattern imaging-position, thus        acquiring the image thus obtained as a second object-image; and    -   a second positional-relationship calculation process that moves        the second reference-image and the second object-image in        relative terms so as to superimpose the second positioning        pattern of the second reference-image and the second positioning        pattern of the second object-image, so that a second        positional-relationship which is the relative        positional-relationship between the second positioning pattern        of the reference chip and the second positioning pattern of the        bonding object chip from the amount of said movement is        calculated; and    -   positions of the bonding pads are calculated based upon the        first positional-relationship and second        positional-relationship, and bonding is performed.

In the above bonding program of the present invention, it is preferablethat

-   -   the inclination-angle calculation process include:        -   a reference conversion origin specifying process that            specifies the conversion origin that is used to subject the            first reference-image to a polar coordinate conversion;        -   a reference-image conversion process that performs a polar            coordinate conversion on the first reference-image by way of            using the specified reference conversion origin, thus            producing a post-conversion reference-image;        -   an object conversion origin specifying process that            specifies the conversion origin that is used to subject the            first object-image to a polar coordinate conversion by a            positional-relationship that is the same as the            positional-relationship between the first positioning            pattern and the reference conversion origin in the first            reference-image, based upon the calculated first            positional-relationship;        -   an object-image conversion process that performs a polar            coordinate conversion on the first object-image by way of            using the specified object conversion origin, thus producing            a post-conversion object-image; and        -   a relative inclination-angle calculation process that moves            the post-conversion object-image and post-conversion            reference-image in relative terms on the angular axis so            that the first positioning pattern that has been subjected            to a polar coordinate development in the post-conversion            object-image and the first positioning pattern that has been            subjected to a polar coordinate development in the            post-conversion reference-image are superimposed, so that            the relative inclination-angle between the positioning            pattern of the reference chip and the positioning pattern of            the bonding object chip is calculated from the angular            amount of said movement; and    -   the reference conversion origin specifying process include:        -   a rotated image acquisition process that acquires a rotated            image produced by rotating the first reference-image through            a specified angle, and        -   a pattern matching process that moves the first            reference-image and the rotated image in relative terms,            thus performing pattern matching so that the positioning            pattern of the first reference-image and the positioning            pattern of the rotated image are superimposed; and    -   a reference conversion origin, which is such that the error in        the relative positional-relationship between the two positioning        patterns detected by pattern matching of an image that is the        object of comparison obtained by imaging-positioning patterns        disposed in an attitude that includes positional deviation in        the direction of rotation, and a first reference-image obtained        by imaging-positioning patterns containing no positional        deviation in the direction of rotation, shows a minimal value,        is specified, based upon the results of the pattern matching.

As seen from the above, in the present invention, the inclination-angleof the first positioning pattern of the bonding object chip iscalculated, and the imaging range of the next second positioning patternis calculated based upon this inclination-angle. Accordingly, even incases where the positioning patterns have an inclination-angle, morerapid movement of the camera to the next imaging-position is possible,and the speed of bonding increases even further.

Furthermore, in the detection of the inclination-angle, a point which issuch that the error in the position of the object of comparison that isdetected by pattern matching between the reference-image and acomparison object-image obtained by imaging an object of comparison thatis disposed in an attitude that includes positional deviation in thedirection of rotation shows a minimum value is used as the origin of thepolar coordinate conversion; as a result, the inclination of the bondingpositioning pattern can be detected more quickly and with greaterprecision. Accordingly, even in cases where the positioning patternshave an inclination-angle, the camera can be moved even more quickly tothe next imaging-position, and the speed of bonding can be increasedeven further.

Furthermore, since the inclination of the bonding positioning patterncan be detected with greater precision, the next imaging range can bemade narrower. Accordingly, the processing time can be reduced evenfurther.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows how the positioning patterns are disposed in a case wherethe bonding object chip is not inclined with respect to the referencechip in the related art;

FIG. 2 shows how the positioning patterns are disposed in a case wherethe bonding object chip is inclined with respect to the reference chipin the related art;

FIG. 3 shows how the center position of the imaging range that is to beimaged next is determined according to the principle of the presentinvention;

FIG. 4 shows the reference-image;

FIGS. 5A and 5B show how a positioning pattern disposed at aninclination as the object of comparison is imaged, and how the positionof the positioning pattern constituting the object of comparison isdetermined by pattern matching with the reference-image;

FIGS. 6A and 6B show the conditions of the polar coordinate conversionof the reference-image according to the present invention;

FIGS. 7A and 7B show the conditions of the polar coordinate conversionof the object-image according to the present invention;

FIGS. 8A and 8B show how the polar coordinate conversion of thereference-image is performed based upon the principle of the presentinvention;

FIGS. 9A and 9B show how the polar coordinate conversion of theobject-image is performed based upon the principle of the presentinvention;

FIG. 10 shows how the inclination-angle Δθ is determined based upon theprinciple of the present invention;

FIG. 11 is a block diagram of the wire bonding apparatus in anembodiment of the present invention;

FIG. 12 is a flow chart showing the procedure of the calculation of thepositions of the positioning patterns in an embodiment of the presentinvention;

FIG. 13 illustrates one example of inclination-angle detection;

FIG. 14 is a detailed internal flow chart of the inclination-angledetection in Embodiment 2;

FIG. 15 is a detailed internal flow chart of the reference conversionorigin specifying step in Embodiment 3;

FIG. 16 is a diagram showing the relationship between the positioningpatterns and the external shape of the reference chip for thereference-image;

FIG. 17 is a diagram showing the conditions of the rotated image that isobtained by rotating the reference-image +Q° about the lower left cornerpoint in the reference-image in Embodiment 3;

FIG. 18 is a diagram showing the conditions of pattern matching betweenthe reference-image and the rotated image obtained by rotating thereference-image +Q° in Embodiment 3;

FIG. 19 is a diagram showing the conditions of the rotated image that isobtained by rotating the reference-image −Q° about the lower left cornerpoint in the reference-image in Embodiment 3;

FIG. 20 is a diagram showing the conditions of pattern matching betweenthe reference-image and the rotated image obtained by rotating thereference-image −Q° in Embodiment 3;

FIG. 21 is a diagram illustrating the content of the equation used todetermine the reference conversion origin in Embodiment 3;

FIG. 22 is a detailed internal flow chart of the reference conversionorigin specifying step in Embodiment 4; and

FIG. 23 shows how a plurality of rotational center points are set withinthe reference-image in Embodiment 4.

DETAILED DESCRIPTION OF THE INVENTION

1. Relationship Between Inclination-angle and Imaging-position

FIG. 3 shows how the coordinates (X₄, Y₄) of the position 256 of thesecond positioning pattern of the bonding object chip 230 which is thecenter position of the imaging range 250 that is to be imaged next aredetermined from the three data of the coordinates (X₁, Y₁) of theposition 206 of the first positioning pattern 202 and coordinates (X₂,Y₂) of the position 216 of the second positioning pattern 212 of thereference chip 200, and the coordinates (X₃, Y₃) of the position 236 ofthe first positioning pattern 232 of the bonding object chip 230, in adisposition relationship similar to that of FIG. 2. The X axis and Yaxis are taken in the directions shown in FIG. 3.

Here, it is assumed that the length L of a line segment connecting theposition coordinates (X₁, Y₁) of the first positioning pattern 202 andthe position coordinates (X₂, Y₂) of the position 216 of the secondpositioning pattern 212 in the reference chip 200, and the angle θ₂ ofthis line segment with respect to the X axis, are already known;furthermore, it is assumed that the inclination-angle Δθ of the firstpositioning pattern 232 of the bonding object chip 230 is determinedusing a conventional technique.

Accordingly, if the angle with respect to the X axis of a line segmentconnecting the coordinates (X₃, Y₃) of the position 236 of the firstpositioning pattern 232 and the coordinates (X₄, Y₄) of the position 256of the second positioning pattern 252 in the bonding object chip 230 isdesignated as θ₁, the following relationship equations hold true:θ₁=θ₂+Δθ  (5)θ₂=arcTan {(Y ₂ −Y ₁)/(X ₂ −X ₁)  (6)L=√{(X ₂ −X ₁)²+(Y ₂ −Y ₁)²}  (7)X ₄ =X ₃ +Lcos θ₁  (8)Y ₄ =Y ₃ +Lsin θ₁  (9)

Thus, by detecting the inclination-angle Δθ of the first positioningpattern 232 of the bonding object chip 230, and performing thecalculations of Equations (5) through (9) based upon this detectedangle, it is possible to obtain (X₄, Y₄), which are the center positioncoordinates of the next imaging range 250. By moving the camera to thisposition at a high speed, it is possible to capture the next positioningpattern 252 in the center of the imaging range of the camera even if thefirst positioning pattern 232 of the bonding object chip 230 isinclined. 2. Principle of Improvement of Precision of Inclination-angle

The next positioning pattern 252 can be captured in the center of theimaging range of the camera by way of using the above-describedrelationship between the inclination-angle and the imaging-position; inthis case, this positioning pattern can be captured further toward thecenter of the imaging range as the detection precision of theinclination-angle is improved. Specifically, even if the imaging rangeis narrowed, the next positioning pattern 252 can be captured in thisrange, and the processing time required for positioning can be shortenedeven further. Accordingly, the improvement of the precision of theinclination-angle will be described next.

The present invention is based on the results of an investigation of thequestion of where to locate the origin in the detection of angles by wayof using a polar coordinate conversion in order to achieve greaterprecision. In the prior art, as described above, the precision isinfluenced by the manner in which the origin is established inperforming a polar coordinate conversion. Accordingly, when a pointshowing relative immunity to the effects of rotation was investigated,the rotation-resistant reference point of Japanese Patent ApplicationLaid-Open (Kokai) No. 2002-208010 attracted attention. Therotation-resistant reference point in the same reference is not used todetermine angles. However, as described above, this point is “a pointwhich is such that the error in the position of the object of comparisonthat is detected in pattern matching of the reference-image and an imageof the object of comparison that is obtained by imaging the object ofcomparison disposed in an attitude that includes positional deviation inthe direction of rotation shows a minimum value”.

Accordingly, it was thought that this point could be viewed as a pointthat is relatively unaffected even if there is rotation, and that itmight be possible to perform a stable polar coordinate conversion evenin the case of asymmetrical patterns by way of using this point as theorigin of the polar coordinate conversion. As a result of thisinvestigation, it was found that inclination-angles can be detected withgood precision, while reducing the quantity of calculations required, bytaking this rotation-resistant reference point as origin of the polarcoordinate conversion. This will be described in detail below withreference to the accompanying drawings.

First, the fact that it is difficult to determine inclination-angleswith sufficient precision even if a positional reference pointdetermined by ordinary pattern matching is used as the origin of a polarcoordinate conversion will be illustrated using FIGS. 4 through 7. Next,the fact that inclination-angles can be determined with good precisionif a rotation-resistant reference point is used as the origin of thispolar coordinate conversion will be illustrated using FIGS. 8 through10.

FIG. 4 shows the conditions of a reference-image 10 that is imaged so asto include a positioning pattern Po. For example, an image that isobtained by imaging the positioning pattern Po with a reference chipused as a positioning reference in a reference position is used as thereference-image 10. In the example shown in FIG. 4, the positioningpattern Po is imaged as a square pattern that is parallel to thelongitudinal axis and horizontal axis of the reference-image. Forexample, the center position 20 of the reference-image 10 can be takenas an indicator of the position of the positioning pattern Po. Here,furthermore, the “positioning pattern Po” refers not to the positioningpattern that is used to position the image itself, but rather to theportion of the positioning pattern that is imaged within the image.However, this is abbreviated, and is simply called the “positioningpattern”. Accordingly, when the term “positioning pattern” is usedbelow, there may be cases in which this indicates the positioningpattern on the surface of the chip prior to imaging, and cases in whichthis indicates the portion of the positioning pattern that is imagedwithin the image following the imaging of this positioning pattern.

FIG. 5A shows the conditions of a positioning pattern P₂ that isdisposed at an inclination as the object of comparison. When imaging isperformed with a camera, only the positioning pattern P₂ disposed at aninclination is obtained. Here, the image region corresponding to FIG. 4is indicated as the image region 12 in FIG. 5A, and the center positionof this image region 12 is indicated as 22. Since the image region 12and center position 22 vary in association with the inclination of thepositioning pattern, the center position 22 in FIG. 5A indicates thetrue position of the positioning pattern P₂ disposed at an inclination.

FIG. 5B shows how the position of the positioning pattern P₂ that is theobject of comparison is determined by pattern matching. In patternmatching, the reference-image 10 is moved parallel to the longitudinalaxis and horizontal axis so that the positioning pattern P₀ andpositioning pattern P₂ disposed at an inclination are superimposed.Since the two positioning patterns are inclined with respect to eachother, the positioning patterns are not completely superimposed.However, the movement is stopped in the position showing the greatestdegree of overlapping. The positioning pattern P₄ following movement inthis case is shown along with the reference-image 14 and center position24 in FIG. 5B. In pattern matching, the center position 24 in this caseis taken as an indicator of the position of the positioning pattern P₂that is the object of comparison. Specifically, the difference betweenthe center position 20 taken as a positioning reference and the centerposition 24 obtained by pattern matching as described above is taken asan indicator of the positional deviation between the positioning patternP₀ of the reference-image and the positioning pattern P₂ that is theobject of comparison.

As shown in FIG. 5B, the center position 24 that is taken as theposition of the positioning pattern P₂ that is the object of comparisonin pattern matching differs from the center position 22 that is the trueposition of the positioning pattern P₂ constituting the object ofcomparison. If the positioning pattern that is the object of comparisonis not inclined, then such a difference is not generated. However, ifthe positioning pattern that is the object of comparison is disposed atan inclination, then a difference is generated between the position ofthe object of comparison thus determined by pattern matching and thetrue position.

The conditions of the polar coordinate conversion of the positioningpatterns P₀ and P₂ are shown in FIGS. 6 and 7. FIGS. 6A and 7A show thepositioning patterns P₀ and P₂ prior to the polar coordinate conversion,and FIGS. 6B and 7B show the positioning patterns P₆ and P₈ followingthe polar coordinate conversion, using the axis in the direction of theradius r and the axis in the direction of the angle θ. FIGS. 6A and 6Bshow the conditions of the polar coordinate conversion of thepositioning pattern P₀ of the reference-image 10. The center position 20illustrated in FIG. 4 is used as the origin of the polar coordinateconversion. FIGS. 7A and 7B show the conditions of the polar coordinateconversion of the positioning pattern P₂ that is disposed at aninclination; the center position 24 obtained in the pattern matchingillustrated in FIG. 5 is used as the origin of the polar coordinateconversion in this case.

The relative inclination-angle between the positioning patterns P₀ andP₂ is determined from a comparison of the positioning patterns P₆ and P₈following the polar coordinate conversion. Specifically, bothpositioning patterns P₆ and P₈ are caused to move in relative termsalong the angular axis, and this movement is stopped in the positionwhere the positioning patterns show the greatest degree of overlapping;the inclination-angle can be determined based upon the movement angle.However, the positioning pattern P₆ shown in FIG. 6B and the positioningpattern P₈ shown in FIG. 7B differ considerably in terms of theconditions of these positioning patterns, so that the inclination-anglecannot be determined with sufficient precision even if pattern matchingis performed on the angular axis. If the center position 22 indicatingthe true position illustrated in FIG. 5 is taken as the origin of thepolar coordinate conversion in FIG. 7A, then the conditions of thepositioning pattern following this polar coordinate conversion are closeto those shown in FIG. 6B; accordingly, it may be predicted that theinclination-angle can be determined with some degree of precision.However, since the inclination of the positioning pattern P₂ isnecessary for the calculation of the center position 22 shown in FIG. 5,the problem returns in a vicious circle, so that resolution isdifficult.

Thus, the pattern obtained by a polar coordinate conversion variesgreatly according to the placement of the origin of the polar coordinateconversion, and the precision of angle detection is influenced by this.Furthermore, as described above, in cases where the positioning patternthat is the object of comparison is disposed at an inclination, theinclination-angle cannot be determined with satisfactory precision evenif the position determined by ordinary pattern matching is used “as is”as the origin of the polar coordinate conversion.

Next, a case in which a rotation-resistant reference point is taken asthe origin of the polar coordinate conversion will be described. Inorder to facilitate comparison, the positioning patterns used are thesame as those shown in FIGS. 6 and 7. In this case, since thepositioning patterns are square, the rotation-resistant reference pointis the center point of the square positioning pattern regardless ofwhich of the two embodiments described in Japanese Patent ApplicationLaid-Open (Kokai) No. 2002-208010 is used. Furthermore, even if thepositioning patterns have an asymmetrical shape, results that aresimilar to those described below are obtained if the rotation-resistantreference point is determined according to the two embodiments ofJapanese Patent Application Laid-Open (Kokai) No. 2002-208010, and thispoint is taken as the origin of the polar coordinate conversion.

FIGS. 8 and 9 show the conditions of a polar coordinate conversionperformed for the positioning patterns P₀ and P₂ with thisrotation-resistant reference point set as the origin 26. FIGS. 8A and 9Ashow the positioning patterns P₀ and P₂ prior to the polar coordinateconversion, and FIGS. 8B and 9B show the positioning patterns P₁₀ an P₁₂following the polar coordinate conversion, using the axis in thedirection of the radius r and the axis in the direction of the angle θ.FIGS. 8A and 8B show the conditions of the polar coordinate conversionof the positioning pattern P₀ of the reference-image 10, and FIGS. 9Aand 9B show the conditions of the polar coordinate conversion of thepositioning pattern P₂ that is disposed at an inclination. The origins26 and 28 of these polar coordinate conversions are both the centers ofthe square shapes of the positioning patterns P₀ and P₂ as describedabove.

FIG. 10 shows the image that is thus obtained following the polarcoordinate conversion performed on the reference-image 10 as describedabove and the image that is obtained following the polar coordinateconversion performed on the image that is the object of comparison,arranged on the same angular axis. Thus, the positioning patterns P₁₀and P₁₂ following the polar coordinate conversion have shapes that arerelatively easy to compare. The deviation Δθ in the direction of theangular axis is determined from this comparison, and this is theinclination-angle of the positioning pattern P₂ with respect to thepositioning pattern P₀.

Furthermore, polar coordinate conversion for the object of comparison isperformed over 360°. However, as seen from FIG. 10, it is not alwaysnecessary to perform this conversion over 360° for the reference-image10 if a polar coordinate conversion can be performed for a sufficientlylarge angular range with respect to the inclination-angle Δθ. Forexample, in a case where it is attempted to detect the inclination-anglewithin Δθ₀, a polar coordinate conversion can be performed in an angularrange of (360°-2Δθ₀). Furthermore, the radius r of the polar coordinateconversion can be set arbitrarily. However, if this radius is set at avalue that is too small, the amount of information from the positioningpatterns P₀ and P₂ is reduced, and there may be cases in which this hasan effect on the detection precision of the inclination-angle.Preferably, this radius is set at the smallest radius that canaccommodate all of the positioning patterns P₀ and P₂. By thus keepingthe angular range and radius of the polar coordinate conversion atminimum values, it is possible to shorten the processing time of thepattern matching performed for the image following the polar coordinateconversion.

As described above, it was found that the inclination-angle can bedetected with good precision while reducing the amount of calculationrequired by taking a rotation-resistant reference point as the origin ofthe polar coordinate conversion. The bonding pattern discrimination ofthe present invention was devised based upon this result.

The present invention will be described in detail below with referenceto the accompanying drawings. Below, the present invention will bedescribed using a wire bonding apparatus that bonds wires to commonsemiconductor chips. However, the wire bonding apparatus used may alsobe a wire bonding apparatus that is used for stacked ICs in which chipshave other chips stacked on top. In the following description,furthermore, dedicated positioning patterns disposed on the surfaces ofthe chips are used as the positioning patterns utilized in bonding.However, bonding pads disposed on the diagonal lines of the chips mayalso be used as positioning patterns.

Embodiment 1

FIG. 11 is a block diagram of a wire bonding apparatus 100 using thebonding pattern discrimination method of the present invention.Furthermore, a reference chip 200 or bonding object chip 230 used todiscriminate the positioning pattern is also shown, although this is nota constituent element of the wire bonding apparatus 100.

The wire bonding apparatus 100 comprises an apparatus main body 102 anda control section 120. The apparatus main body includes a bonding head104, a table 106 which moves the bonding head 104 within the XY planeshown in FIG. 8, and a stage 108 that holds the chips 200, 230. A tool110 which bonds a wire to the chips, and a camera 112 which detects thepositions of the chips 200, 230, are attached to the bonding head 104.The bonding head 104 is connected to the bonding head I/F 130 of thecontrol section 120 by a signal line. Similarly, the camera 112 isconnected to the camera I/F 132, and the table 106 is connected to thetable I/F 134, via respective signal lines.

The control section 120 has the function of controlling the overalloperation of the elements that constitute the apparatus main body 102.In particular, this control section 120 has the functions of calculatingthe positions of the positioning patterns, and performing wire bondingbased upon the results of this calculation. Such a control section 120can be constructed from a general computer, or a computer that isespecially meant for use in a bonding apparatus.

The control section 120 includes a CPU 122, an input means 124 such as akeyboard or input switch, etc., an output means 126 such as a display,etc., a memory 128 which stores image data, etc., and theabove-described bonding head I/F 130, camera I/F 132 and table I/F 134;and these elements are connected to each other by an internal bus.

The CPU 122 includes a positioning pattern position calculating section136 which has the function of performing processing that calculates thepositions of the positioning patterns, and a bonding processing section138 which has the function of setting the wire bonding conditions andperforming wire bonding processing based upon the calculated positionsof the positioning patterns. Software can be used to perform suchprocessing; specified processing can be performed by executingcorresponding bonding pattern discrimination programs and bondingprograms. Furthermore, some of the processing may also be performed byhardware.

Details of the functions from the first reference-image acquisitionmodule 140 to the second positional-relationship calculating module 154of the positioning pattern position calculating section 136, and thefunction of the bonding processing section 138, will be described withreference to the flow chart shown in FIG. 12. Symbols corresponding tothe symbols shown in FIGS. 3 and 11 will be used.

First, the reference chip 200 is set (S100). More specifically, a chipused as a reference for the discrimination of the inclination ofpositioning pattern is set as the reference chip 200, and this chip isheld on the stage 108. Next, the camera 112 is moved, and is brought toa position in which the imaging field can capture the first positioningpattern 202 of the reference chip 200 (S102).

Then, an image including the first positioning pattern 202 is acquired,and this image is stored in memory as the first reference-image (S104).More specifically, the first reference-image acquisition module 140sends instructions to the camera 112 via the camera I/F 132, the firstpositioning pattern 202 of the reference chip 200 is imaged, and thisdata is stored in the memory 128. The acquired image corresponds to thefirst reference-image 204 shown in FIG. 3. The camera 112 is providedwith a function that superimposes crosshairs on the image in order toindicate a reference for the imaging range; the intersection point ofthese crosshairs is the center position 206 of the imaging range. Thisposition is used as the position of the first positioning pattern 202.The coordinates of the center position 206 correspond to (X₁, Y₁) shownin FIG. 3.

Next, the camera 112 is moved, and is brought to a position where theimaging visual field can capture the second positioning pattern 212 ofthe reference chip 200 (S106).

Then, an image including the second positioning pattern 212 is acquired,and this image is stored in memory as the second reference-image (S108).More specifically, the second reference-image acquisition module 148sends instructions to the camera 112 via the camera I/F 132, the secondpositioning pattern 212 of the reference chip 200 is imaged, and thisdata is stored in the memory 128. The acquired image corresponds to thesecond reference-image 214 in FIG. 3. The center position 216 of theimaging range in this case is used as the position of the secondpositioning pattern 212. The coordinates of the center position 216correspond to (X₂, Y₂) shown in FIG. 3.

The steps up to this point are a training process that uses thereference chip 200; and running steps that use the bonding object chip230 are performed next.

In the running steps, the bonding object chip 230 is first set (S110).Specifically, the reference chip 200 is removed from the stage 108, andthe chip 230 that is the object of bonding work is set on the stage 108.Then, the camera 112 is moved (S112), imaging is performed in the samevisual field position as that in which the first reference-image 204 wasimaged, and this image is stored in the memory 128 as the firstobject-image (S114). More specifically, the first object-imageacquisition module 142 sends instructions to the camera 112 via thecamera I/F 132, the first positioning pattern 232 of the bonding objectchip 230 is imaged, and this data is stored in the memory 128. Theacquired first object-image corresponds to an image of the imaging field220 including the bonding object chip 230 in FIG. 3.

Next, pattern matching is performed between the first reference-image204 and first object-image, and a first positional-relationship which isthe relative positional-relationship between the first positioningpattern 202 of the reference chip 200 and the first positioning pattern232 of the bonding object chip 230 is calculated (S116). Morespecifically, the first positional-relationship calculating module 144reads out the first reference-image 204 and first object-image from thememory 128, disposes the first object-image and first reference-imagewith the origins of the imaging visual fields aligned, and moves bothimages parallel to each other so that the overlapping of the firstpositioning pattern of the first reference-image and the firstpositioning pattern of the first object-image shows a maximum value. Forexample, normalized correlation calculations can be used as patternmatching method. As a result of this pattern matching, the centerposition of the first reference-image moves from the original centerposition 206 to the center position 236; this moved position isdetermined. This moved position indicates the relative position of thefirst positioning pattern 232 of the first object-image with referenceto the center position 206 of the first reference-image 204. Theposition of the first positioning pattern 232 of the first object-imageobtained as a result of pattern matching corresponds to the coordinates(X₃, Y₃) shown in FIG. 3.

Next, using the first positioning pattern 202 of the firstreference-image 204 as a reference, the inclination-angle of the firstpositioning pattern 232 of the first object-image is calculated (S118).The calculation of this inclination-angle can be accomplished using aconventional technique. For example, FIG. 13 shows how inclination-angledetection is accomplished using the edge detection method. In FIG. 13,when a pattern 262 such as a positioning pattern, etc., is obtained inthe imaging field 260, the angle Δθ formed by this pattern with respectto the reference axis can be determined by detecting the edge 264.Furthermore, an embodiment that further increases the detectionprecision of the inclination-angle will be described later inEmbodiments 2 through 4. The calculated inclination-angle corresponds toΔθ shown in FIG. 3.

The next imaging-position is calculated based upon the calculatedinclination-angle Δθ and the coordinates (X₁, Y₁), (X₂, Y₂) and (X₃, Y₃)(S120). More specifically, the imaging-position calculating module 150performs the calculations of the above-described Equations (5) through(9) using the above-described data, thus calculating the coordinates(X₄, Y₄), and these coordinates are taken as the center position of thenext imaging-position. The calculation results correspond to the imagingrange 250 shown in FIG. 3.

If the respective coordinates and inclination-angles Δθ are calculatedwithout error, the center position of the imaging range 250 in FIG. 3should coincide with the position of the second positioning pattern 252of the bonding object chip 230. In actuality, however, error occurs inthe respective measurements and respective calculations; accordingly,the position of the second positioning pattern 252 of the bonding objectchip 230 is next determined by pattern matching. Specifically, thecamera is moved to the calculated imaging-position (S122), the secondpositioning pattern 252 of the bonding object chip 230 is imaged in thisposition, and this image is stored in the memory 128 as the secondobject-image (S124). More specifically, the second object-imageacquisition module 152 sends instructions to the camera 112 via thecamera I/F 132, so that the second positioning pattern 252 of thebonding object chip 230 is imaged, and this data is stored in the memory128. The acquired second object-image corresponds to the imaging rang250 including the bonding object chip 230 in FIG. 3.

Next, pattern matching is performed between the second reference-image214 and second object-image, so that a second positional-relationshipwhich is the relative positional-relationship between the secondpositioning pattern 212 of the reference chip 200 and the secondpositioning pattern 252 of the bonding object chip 230 is calculated(S126). More specifically, the second positional-relationshipcalculating module 154 reads out the second reference-image 214 andsecond object-image from the memory 128, and performs pattern matchingby the same method as that described for the firstpositional-relationship calculation step (S116). The position of thesecond positioning pattern 252 of the second object-image that isobtained as a result of pattern matching corresponds to the point 256 inFIG. 3.

Thus, by detecting the inclination-angle Δθ and calculating Equations(5) through (9), it is possible to move the camera at a high speed tothe next imaging-position, and to obtain the position of the secondpositioning pattern for the bonding object chip 230. Once the positionsof the first positioning pattern and second positioning pattern havethus been determined in the running steps, the processing required forwire bonding is performed by the function of the bonding processingsection 138. For example, the positions of the respective bonding padsof the bonding object chip are calculated based upon the positions ofthe first positioning pattern and second positioning pattern (S128).Then, an instruction to move the tool 110 to the corrected bonding padpositions is sent to the table 106 via the table I/F 134, and when thetool 110 is moved to these positions, instructions are sent to thebonding head 104 via the bonding head I/F 130 so that the operations ofthe tool that are required for wire bonding are performed, thusresulting in the performance of wire bonding (S130).

Embodiment 2

An embodiment in which a polar coordinate conversion is used as themethod of detecting the inclination-angle of the positioning patternswill be described with reference to the flow chart shown in FIG. 14. Theflow chart shown in FIG. 14 summarizes the procedure used to determinethe inclination-angles of the positioning patterns separately from theflow chart shown in FIG. 12. Accordingly, when this flow chart iscombined with the flow chart shown in FIG. 12, it is necessary to omitthe duplicated steps. Furthermore, in the flow chart shown in FIG. 12,the designations “first” and “second” are used in order to distinguishthe two positioning patterns. However, since the following descriptionrelates to the procedure used to determine the inclination-angle for asingle positioning pattern, the designation of “first” is omitted, andthe patterns are referred to simply as the “reference pattern” and“positioning pattern”.

Furthermore, since it is convenient to use the description in FIGS. 4through 10 to describe the principle of the polar coordinate conversion,patterns with a rectangular shape such as bonding pads will be describedbelow as the positioning patterns. In regard to the conditions of theimages corresponding to the respective steps, corresponding conditionsin FIGS. 4 through 10 will be indicated when necessary. Furthermore, thesymbols used are the symbols of FIG. 11. Furthermore, the contentsdescribed below are executed as functions of internal modules of the CPU122.

First, the reference chip 200 is set (S10). More specifically, a chipthat acts as a reference for the discrimination of the inclination ofthe positioning patterns is used as a reference chip 200, and this chipis held on the state 108. Next, the camera 112 is moved, and is broughtto a position which is such that the imaging visual field can capturethe positioning pattern P₀ of the reference chip 200 (S12).

Then, an image including the positioning pattern P₀ is acquired, andthis image is stored in memory as a reference-image (S14). Morespecifically, the CPU 122 sends instructions to the camera 112 via thecamera I/F 132 so that the positioning pattern P₀ of the reference chip200 is imaged, and this data is stored in the memory 128. The acquiredimage corresponds to the reference-image 10 in FIG. 1. The camera 112 isprovided with a function that superimposes cross-hairs on the image inorder to indicate the reference of the imaging range, and theintersection point of these cross-hairs is the center position 20 of theimaging range. In subsequent processing relating to the image, thesecross-hairs are used as reference coordinate axes, and the centerposition 20 constituting the intersection point is used as thecoordinate origin.

Next, the reference conversion origin which is the origin used for thepolar coordinate conversion is specified for this reference-image 10(S16). More specifically, the CPU 122 calculates the rotation-resistantreference point described in the “Principle of Improvement of Precisionof Inclination-angle” of the present invention based upon the data ofthe reference-image 10 stored in the memory 128, and specifies thesecoordinates as the reference conversion origin. Furthermore, asdescribed above, the coordinates of the reference conversion origin arespecified using the center position 20 as a reference. The more detailedcontent of this process will be described later in Embodiment 2 andEmbodiment 3. The specified reference conversion origin corresponds tothe origin 26 in FIG. 8.

The reference-image 10 is subjected to a polar coordinate conversionusing the specified reference conversion origin (S18), and the resultingimage is stored in the memory 128 as a post-conversion reference-image.More specifically, the CPU 122 reads out the reference-image 10 from thememory 128, determines the coordinates of the specified referenceconversion origin using the center position 20 as a reference, and takesthis origin as the origin of the polar coordinate conversion. Then, forexample, calculations are performed in which the image is varied by anangle of θ in the clockwise direction, and the brightness data of thereference-image are converted as a function of the radius r for eachangle θ. Accordingly, in the reference-image following this conversion,the brightness data are disposed with the horizontal axis taken as theangle θ, and the vertical axis taken as the radius r. Such apost-conversion reference-image corresponds to the image shown in FIG.8B.

The process up to this point is a training process that uses thereference chip 200; next, a running process that uses the bonding objectchip 230 is performed.

In the running process, the bonding object chip 230 is first set (S20).Specifically, the reference chip 200 is removed from the stage 108, andthe chip 230 that is the object of bonding work is set on the stage 108.Then, imaging is performed in the same visual field position as that inwhich the reference-image 10 was acquired, and the resulting image isstored in the memory 128 as an object-image (S22). More specifically,the CPU 122 sends instructions to the camera 112 via the camera I/F 132so that the positioning pattern P₂ of the bonding object chip 230 isimaged, and this data is stored in the memory 128. The acquiredobject-image corresponds to FIG. 5A.

Next, pattern matching is performed between the reference-image 10 andthe object-image, and the relative positional-relationship between thepositioning pattern P₀ of the reference chip 200 and the positioningpattern P₂ of the bonding object chip is calculated (S24). Morespecifically, the CPU 122 reads out the reference-image 10 andobject-image from the memory 128, disposes the object-image andreference-image with the origins of the imaging visual fields aligned,and moves both images parallel to each other so that the overlapping ofthe positioning pattern of the reference-image and the positioningpattern of the object-image shows a maximum value. For example,normalized correlation calculations can be used as pattern matchingmethod. As a result of this pattern matching, the center position of thereference-image moves from the original center position 20 to the centerposition 24; the amount of this movement (ΔX, ΔY) is determined. Thismovement amount (ΔX, ΔY) indicates the relative position of thepositioning pattern of the object-image with reference to the centerposition 20 of the reference-image 10. The conditions of this patternmatching correspond to FIG. 5B.

Next, the object conversion origin which is the origin that is used inorder to subject the object-image to a polar coordinate conversion isspecified (S26). More specifically, the CPU 122 performs the followingcalculations. Specifically, if the coordinates of the referenceconversion origin 26 with reference to the center position 20 aredesignated as (X₂₆, Y₂₆), and the coordinates of the object conversionorigin are designated as (X₂₈, Y₂₈), then the coordinates of this originare (X₂₈=X₂₆+ΔX, Y₂₈=Y₂₆+ΔY). The object conversion origin correspondsto the origin 28 in FIG. 9A.

The object-image is subjected to a polar coordinate conversion using theobject conversion origin thus specified (S28), and the resulting imageis stored in the memory as a post-conversion object-image. Morespecifically, the CPU 122 reads out the object-image from the memory128, determines the coordinates of the specified reference conversionorigin, takes these coordinates as the origin of the polar coordinateconversion, and performs calculations in which, for example, the imageis varied by an angle of θ in the clockwise direction, and thebrightness data of the reference-image is converted as a function of theradius r for each angle θ. Such a post-conversion reference-imagecorresponds to the image shown in FIG. 9B.

Pattern matching is performed for the post-conversion reference-imageand post-conversion object-image thus determined, and theinclination-angle is calculated (S30). More specifically, the CPU 122reads out the post-conversion reference-image and post-conversionobject-image from the memory 128, disposes both images with the originsof the angular axes aligned, moves both images parallel to each otheralong the angular axis, and determines the movement amount Δθ which issuch that the overlapping of the positioning pattern of thepost-conversion reference-image and the positioning pattern of thepost-conversion object-image shows a maximum value. This movement amountΔθ indicates the relative inclination-angle of the positioning patternP₂ of the bonding object chip 230 with reference to the positioningpattern P₀ of the reference chip 200. The conditions of thedetermination of the inclination-angle Δθ are shown in FIG. 10.

Thus, the inclination-angles of the positioning patterns can bedetermined with good precision by calculating the rotation-resistantreference point described in the “Principle of Improvement of Precisionof Inclination-angle” of the present invention, specifying thecoordinates of this point as the reference conversion origin, andperforming a polar coordinate conversion using this origin.

Accordingly, the imaging-position in which the next positioning patternis imaged can be determined with a higher degree of precision, so thatthe next positioning pattern can be captured more securely even if theimaging range is narrowed. An example of this is indicated by thenarrower imaging range 270 shown in FIG. 3. By making the imaging rangenarrower, it is possible to reduce the amount of processing required forpattern matching in this region, and to shorten the processing time.

Embodiment 3

The more detailed content of the reference conversion origin specifyingstep (S16) will be described. Embodiment 3 corresponds to an embodimentin which the first embodiment in the above-described Japanese PatentApplication Laid-Open (Kokai) No. 2002-208010 is applied to the bondingpositioning patterns. The detailed content of this reference conversionorigin specifying step will be described with reference to the internalflow chart shown in FIG. 15, and FIGS. 16 through 21. In FIG. 15, andFIGS. 16 through 21, elements that are the same as elements shown inFIGS. 4 and 5 are labeled with the same symbols, and a detaileddescription of such elements is omitted. Furthermore, the procedureshown in the internal flow chart in FIG. 15 is performed by internalmodules in the CPU 122 illustrated in FIG. 11.

The reference-image 10 acquired by the steps S10 through S14 illustratedin FIG. 14 is used to specify the reference conversion origin. FIG. 16is a diagram which again shows the relationship between the positioningpattern P₀ and the external shape of the reference chip 200 for thereference-image 10. FIG. 14 is similar to FIG. 4. However, it isindicated that the positioning pattern P₀ uses square bonding patternsthat are disposed in the vicinity of the corners of the reference chip200. Furthermore, the range of the reference-image 10 is set on theinside of the outer shape line of the reference chip 200 so that noisefrom this outer shape line cannot enter. In order to indicate that thereis no objection to the disposition of the positioning pattern P₀intersecting with the crosshairs, the disposition of the positioningpattern is slightly different than that shown in FIG. 4. In thesubsequent processing, the crosshairs of the reference-image 10 aretaken as the reference coordinate axes, and the center position 20constituting the intersection point of the crosshairs is taken as theorigin of the reference axes.

Using this reference-image 10, a rotated image obtained by rotating theimage +Q° about one corner of the reference-image 10 is produced (S40).FIG. 17 shows the conditions of the rotated image 40 centered on thepoint 30 at the lower left corner in the reference-image 10.

Next, the point of best matching is determined by pattern matchingbetween the reference-image 10 and the rotated image 40 (S42). Morespecifically, the reference-image 10 is moved parallel to the rotatedimage 40 so that maximum overlapping is obtained between the positioningpattern of the reference-image 10 and the positioning pattern of therotated image 40. The center position in the reference-image 50 in thecase of maximum overlapping is the point of best matching 42 of bothimages. The conditions of this matching are shown in FIG. 18. Thecoordinates of the original center position 20 of the reference-image 10are designated as (0, 0), and the coordinates of the point of bestmatching 42 are designated as (X₁, Y₁) (S44).

Similarly, as shown in FIG. 19, a rotated image 60 that is rotated −Q°about the corner point 30 of the reference-image 10 is produced (S46).Then, the point of best matching of both images is determined by patternmatching between the reference-image 10 and rotated image 60 (S48). Morespecifically, as shown in FIG. 20, the reference-image 10 is movedparallel to the rotated image 60 so that the positioning pattern of thereference-image 10 and the positioning pattern of the rotated image 60show a maximum degree of overlapping. The center position of thereference-image 70 in the case of maximum overlapping is the point ofbest matching 72. The coordinates of the point of best matching 72 aredesignated as (X₂, Y₂) (S50).

The coordinates of the reference conversion origin are calculated usingthe coordinates (X₁, Y₁) of the point of best matching 42 thusdetermined, the coordinates (X₂, Y₂) of the point of best matching 72,the rotational angle Q°, and the coordinates (XC1, YC1) of the cornerpoint 30 taken as the center of rotation (S52). The coordinates (AX1,AY1) of the reference conversion origin are expressed by the Equations(1) through (4) as described above.AX1=XC1+r·cos α  (1)AY1=YC1+r·sin α  (2)Here, α=tan⁻¹{(X ₂ −X ₁)/(Y ₁ −Y ₂)}  (3)r=√{(X ₂ −X ₁)²+(Y ₁ −Y ₂)²}/2sin Q  (4)

FIG. 21 enlarges FIG. 13 in order to illustrate the meaning of theEquations (1) through (4), and shows the corresponding coordinates andangles. Here, the point A₁ is the reference conversion origin for thereference-image 10, and the point A_(m1) is the reference conversionorigin for the reference-image 50. Since the pattern matching isperformed by parallel movement of the reference-images, the accompanyingmovement of the reference conversion origin is the same as the movementof the center position of the reference-image. Specifically, thepositional-relationship of the point A₁ and point A_(m1) is the same asthe positional-relationship of the center positions 20 and 42.

Equation (3) can be explained utilizing the fact that the angle in FIG.16 (point 30-point A₁-point A_(m1)) can be approximated by a right anglein cases where the angle Q is very small. Specifically, if the leg of aperpendicular line dropped to the X axis shown in FIG. 16 from the pointA₁ is designated as point B, and the angle (point A_(m1)-point A₁-pointB) is designated as β, then, from the above-described approximation, theangle (point 30-point A₁-point B)=90°=−β, and the other angle (pintA₁-point B-point 30)=90°. Accordingly, the angle (point A₁-point30-point B)=α=β. Furthermore, since β=tan ¹(X₁Y₁)α=tan¹(X₁/Y₁). Equation(3) is an equation in which this is rewritten as an equation using (X₁,Y₁) and (X₂, Y₂).

Equation (4) can be explained utilizing the fact that the distancebetween the tip ends of mutually equal line segments of a length r onboth sides of the angle Q can be approximated by r x sin Q in caseswhere the rotational angle Q is very small. Specifically, the length ofthe line segment (point A₁-point A_(m1))=r×SinQ =the length of (point20-point 42)=√{(X₁)²+(Y₁)²}; accordingly, r=√{(X₁)²+(Y₁)²}/sinQ isobtained from this. Equation (4) is an equation in which this isrewritten as an equation using (X₁, Y₁) and (X₂, Y₂).

When r and α are thus determined from the coordinates (X₁, Y₁) and (X₂,Y₂) and the rotational angle Q, the coordinates (AX1, AY1) of thereference conversion origin in the reference-image 10 can be calculatedspecified by Equations (1) and (2) using the coordinates (XC1, YC1) ofthe point 30.

The method used to specify the reference conversion origin in Embodiment2 can be used even if the positioning pattern is asymmetrical.Accordingly, the inclination-angle can be calculated with betterprecision, without being influenced by the shape of the positioningpattern.

Embodiment 4

Embodiment 4 corresponds to an embodiment in which the second embodimentin the above-described Japanese Patent Application Laid-Open (Kokai) No.2002-208010 is applied to the bonding positioning pattern with regard tothe reference conversion origin specification step. The detailed contentof this reference conversion origin specification step will be describedwith reference to the internal flow chart shown in FIG. 22, and FIG. 23.The procedure of the internal flow chart shown in FIG. 22 is executed byinternal modules in the CPU 122 illustrated in FIG. 11.

The reference-image 10 acquired in the steps S10 through S14 illustratedin FIG. 14 is also used for the specification of the referenceconversion origin in Embodiment 4.

A plurality of rotational center points are set within thisreference-image 10 (S60). The conditions of this setting are shown inFIG. 23. In this example, a plurality of rotational center points 82 aredisposed at uniform intervals at a fixed spacing within thereference-image 10. The rotational center points can also be disposedwithin the positioning pattern P₀. Preferably, at least one rotationalcenter point is disposed within the positioning pattern P₀. In FIG. 18,the rotational center point 84 is set within the positioning pattern P₀.

Next, for one rotational center point, a rotated image obtained byrotating the reference-image 10+Q° about this point is produced (S62).Then, the amount of matching between the positioning pattern of therotated image thus produced and the positioning pattern of thereference-image 10 is determined (S64). Assuming that each positioningpattern is a bonding pad, and that the brightness data is the same forall pixels, then it may be predicted that the amount of matching will beproportional to the overlapping area of the bonding pads. The steps S62through S64 are performed for each rotational center point (S66 throughS68).

Then, when the amounts of matching have been respectively determined forall of the rotational center points, the rotational center point showingthe maximum amount of matching among these rotational center points isdetermined (S70). Generally, the rotational center point that is closestto the center of the positioning pattern P₀ shows the maximum amount ofmatching. The coordinates of this rotational center point showing themaximum amount of matching are specified as the coordinates of thereference conversion origin (S72). In the example shown in FIG. 23, therotational center point 84 is specified as the reference conversionorigin.

Depending on the manner in which the rotational center points are set,there may be instances in which no exceptional amount of matching isobtained, and the amounts of matching are close to even. In such cases,the rotational center point showing the maximum amount of matching maybe tentatively extracted and the amounts of matching of the surroundingrotational center points may be compared, and the coordinates of aposition that is recognized as being close to the center of thepositioning pattern may be specified as the reference conversion origin.In this case, a specified range from the maximum value of the amount ofmatching is set, a rotational center point that is within this range ora rotational center point that is close to this range is specified, andthis point may be specified as the reference conversion origin.

Compared to the method of Embodiment 3, the method of Embodiment 4 iseasier in terms of the determination of the reference conversion origin,and can greatly reduce the calculation time.

1-4. (canceled)
 5. A bonding apparatus that detects each one ofpositions of a plurality of positioning patterns disposed on a chip thatis an object of bonding, calculates positions of bonding pads that arein a specified positional-relationship with the plurality of positioningpatterns, and performs bonding in calculated positions of said bondingpads, wherein said bonding apparatus comprises: a first reference-imageacquisition means that makes an image of a first positioning patternamong a plurality of positioning patterns for a reference chip which isused as a reference for detection of positions of said positioningpatterns, thus acquiring an image thus obtained as a firstreference-image; a first object-image acquisition means that makes animage of a first positioning pattern for a chip that is an object ofbonding, thus acquiring an image thus as a first object-image; a firstpositional-relationship calculation means that moves a first positioningpattern of said first reference-image and a first positioning pattern ofsaid first object-image in relative terms so as to superimpose both ofsaid images, so that a first positional-relationship which is a relativepositional-relationship between a first positioning pattern of saidreference chip and a fist positioning pattern of said bonding objectchip from an amount of said movement is calculated; an inclination-anglecalculation means that calculates an inclination-angle of the firstpositioning pattern of the bonding object chip with respect to the firstpositioning pattern in the reference chip; a second reference-imageacquisition means that makes an image of a second positioning patternwhich is in a specified positional-relationship with the firstpositioning pattern for the reference chip, thus acquiring an image thusobtained as a second reference-image; an imaging-position calculationmeans that calculates a second positioning pattern imaging-position inwhich a second positioning pattern is imaged for the chip that is anobject of bonding, wherein said second positioning patternimaging-position is calculated based upon the firstpositional-relationship, the inclination-angle, a specifiedinter-pattern positional-relationship and the imaging-position in thefirst object-image acquisition step; a second object-image acquisitionmeans that makes an image of a second positioning pattern for thebonding object chip in the calculated second positioning patternimaging-position, thus acquiring the image thus obtained as a secondobject-image; and a second positional-relationship calculation meansthat moves the second reference-image and the second object-image inrelative terms so as to superimpose the second positioning pattern ofthe second reference-image and the second positioning pattern of thesecond object-image, so that a second positional-relationship which is arelative positional-relationship between the second positioning patternof the reference chip and the second positioning pattern of the bondingobject chip from an amount of said movement is calculated; and positionsof the bonding pads are calculated based upon the firstpositional-relationship and second positional-relationship, and bondingis performed.
 6. The bonding apparatus according to claim 5, whereinsaid inclination-angle calculation means comprises: a referenceconversion origin specifying means that specifies a conversion originthat is used to subject the first reference-image to a polar coordinateconversion; a reference-image conversion means that performs a polarcoordinate conversion on the first reference-image by way of using aspecified reference conversion origin, thus producing a post-conversionreference-image; an object conversion origin specifying means thatspecifies the conversion origin that is used to subject the firstobject-image to a polar coordinate conversion by apositional-relationship that is the same as a positional-relationshipbetween the first positioning pattern and the reference conversionorigin in the first reference-image, based upon a calculated firstpositional-relationship; an object-image conversion means that performsa polar coordinate conversion on the first object-image by way of usinga specified object conversion origin, thus producing a post-conversionobject-image; and a relative inclination-angle calculation means thatmoves the post-conversion object-image and post-conversionreference-image in relative terms on a angular axis so that the firstpositioning pattern that has been subjected to a polar coordinatedevelopment in the post-conversion object-image and the firstpositioning pattern that has been subjected to a polar coordinatedevelopment in the post-conversion reference-image are superimposed, sothat a relative inclination-angle between the positioning pattern of thereference chip and the positioning pattern of the bonding object chip iscalculated from an angular amount of said movement; and said referenceconversion origin specifying means comprises: a rotated imageacquisition means that acquires a rotated image produced by rotating thefirst reference-image through a specified angle, and a pattern matchingmeans that moves the first reference-image and the rotated image inrelative terms, thus performing pattern matching so that the positioningpattern of the first reference-image and the positioning pattern of therotated image are superimposed; and a reference conversion origin. whichis such that an error in the relative positional-relationship betweentwo positioning patterns detected by pattern matching of an image thatis an object of comparison obtained by imaging-positioning patternsdisposed in an attitude that includes positional deviation in adirection of rotation, and a first reference-image obtained byimaging-positioning patterns containing no positional deviation in adirection of rotation, shows a minimal value, is specified, based uponresults of the pattern matching. 7-8. (canceled)